Refining method of N-methyl pyrrolidone product

Abstract

The invention discloses a refining method of an N-methyl pyrrolidone product. A classifying and condensing system is arranged on the upper portion of an N-methyl pyrrolidone product rectifying tower,and comprises two or more temperature-controllable heat exchangers and corresponding refluxing tanks. The refining method comprises the following specific steps: feeding N-methyl pyrrolidone which requires to be purified into a rectifying tower for distilling; carrying out primary condensing on an overhead product of the rectifying tower; feeding a gas-phase product subjected to primary condensinginto a secondary heat exchanger for condensing; feeding a liquid-phase product subjected to primary condensing into a primary refluxing tank; discharging a gas product subjected to secondary condensing; refluxing a liquid-phase product subjected to secondary condensing to the rectifying tower; and refluxing part of the products in the primary refluxing tank to the rectifying tower, and meanwhileextracting the other part of the products as an N-methyl pyrrolidone refined product. The refining method of an N-methyl pyrrolidone product is low in investment, low in energy consumption and easy tooperate, and free amines and light impurities are removed simply and effectively to obtain the high-quality N-methyl pyrrolidone product.

Description

technical field [0001] The invention belongs to the technical field of chemical industry, and in particular relates to a method for refining an N-methylpyrrolidone product. Background technique [0002] Pyrrolidone is a product category widely used in solvent, chemical, pharmaceutical and other industries, including N-methylpyrrolidone (NMP) and N-ethylpyrrolidone (NEP), among which NMP and NEP are both highly selective and stable Good polar solvent, with moderate boiling point, high flash point, low toxicity and strong solubility; Vinylidene fluoride, etc.), lithium-ion battery electrode auxiliary materials, photoresist remover, LCD liquid crystal material production, cleaning of circuit boards in the semiconductor industry, etc.; NEP can be used in medicine, high-grade solvents and other industries. [0003] Taking N-methylpyrrolidone as an example, the existing preparation method of pyrrolidone is: use γ-butyrolactone and methylamine (40%) to carry out thermal condensati...

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Problems solved by technology

Patent CN102001986A needs to use an ion exchange device composed of macroporous adsorption resin, strongly acidic ion exchange resin, and strongly basic ion exchange resin; patent CN102190611A needs to use an ion exchange device composed of nonpolar macroporous resin column and charged cellulose membrane , the methods disclosed in these two patent applications use many types of ion exchange resins, complex operations, and low treatment efficiency, or need to increase organic alcohols, causing secondary pollution to N-methylpyrrolidone products

Patent CN201310019294.8 discloses the method of using ion-exchange fiber to absorb and remove free amine, which has low fiber adsorption efficiency, high moisture and chroma content in the early stage product, and needs to use strong acid and other defects, so it is difficult to implement economically in the industry

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